Rail Vehicle Transformer Pre-magnetization Control
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Solution Overview
Problem
Existing methods for controlling mains converters in rail vehicles fail to effectively suppress 100 Hz harmonics caused by primary-side pre-magnetization, leading to interference currents that can trigger disconnection and malfunction of traction vehicles, especially under conditions like icy overhead lines.
Innovation Solution
A method that detects the direct current component of the mains current using suitable measuring and evaluation devices, and adjusts the current control to counteract pre-magnetization, ensuring the transformer is not pre-magnetized, thereby preventing harmonic-induced interference currents. This can be achieved using either active or passive converters, with the latter reducing manufacturing effort and not requiring additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active mains current transformers are used to detect DC components, then detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention uses passive transformers as intermediaries to couple primary and secondary sides, enabling DC component detection and counteraction through AC signal processing without requiring direct DC measurement hardware on the primary side
Solution Approach 2:
The invention replaces direct DC measurement (requiring specialized active sensors) with indirect detection through AC signal analysis using standard passive transformers and electronic processing, substituting hardware complexity with signal processing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures reliable operation of traction vehicles by preventing transformer pre-magnetization, reducing the risk of harmonic-induced failures and maintaining constant intermediate circuit voltage, even under adverse conditions like icy catenary with arcing.
Implementation Method 1
a mains voltage of a single-phase AC network being fed to a primary winding of a transformer via a pantograph
Implementation Method 2
a constant DC link voltage being generated at the mains converter on the output side
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method for controlling a power converter (3) for rail vehicles, wherein a power supply current (iNetz) is supplied to the power converter (3) via a transformer (2) by means of a current collector (1) which taps a power supply voltage (uNetz) of a single-phase AC network, and a constant DC link voltage (ud) is generated on the output side of the power converter (3), wherein a DC component of the power supply current (iNetz) is detected on the primary side of the transformer by means of suitable measuring and evaluation devices (8, 9, 15 or 9a, 15a) and wherein a DC setpoint (iQSoll,DC) corresponding to the DC component is superimposed on a current setpoint (iQSoll) of a secondary-side current control (12) of the power converter (3) in such a way that a secondary-side DC current set by the current control (12) counteracts a premagnetization of the transformer (2).